This invention relates to an improved squeeze film damper seal, and more particularly, to an improved piston ring seal and groove combination with adjustable piston ring sealing, for squeeze film dampers as associated with high speed turbo machinery, for example, hot gas turbine engines such as aircraft gas turbine engines.
In a prior typical squeeze film shaft damper arrangement, a shaft with its associated rolling element bearing are permitted to have some limited radial motion in the supporting bearing housing. Ordinarily an annular outer race of a supporting rolling element bearing of a shaft closely fits in an annular chamber in the support housing where two opposing closely adjacent circumferential surfaces of the housing and race define a thin annular squeeze film space into which an oil under pressure is introduced for damping action on the race. The race is fitted with spaced apart concentric piston ring type seals which circumferentially engage the bearing housing to seal off the squeeze film space between the rings. One problem with dampers as described, is sealing of the fluid film squeeze film space by means of the described piston ring seals under the known variable operating conditions of the damper. For example, the noted variable operating conditions include fluid pressure fluctuations adjacent the rings which lead to sealing instability of the rings and excess damper fluid leaking with compromised damper effectiveness. Furthermore, sealing ring and damper effectiveness may not be constant for different levels of turbine operation.